A novel non-segmented double-stranded RNA virus isolated from the basal fungus Conidiobolus sp.

Mycoviruses are widely distributed in a variety of fungal species. However, few viruses have been reported in basal fungi. A novel non-segmented dsRNA virus was isolated from the basal fungus Conidiobolus sp. of the phylum Zoopagomycota, which has been named "Conidiobolus non-segmented RNA virus 1" (CNRV1). The complete genome sequence of CNRV1 was determined by dsRNA extraction, next-generation sequencing, and RACE. The genome of CNRV1 dsRNA is 3,092 bp in length and contains two open reading frames (ORFs) predicted to encode a subgenomic protein 1 (sgP1) and a putative RNA-dependent RNA polymerase (RdRp). Multiple sequence alignment and phylogenetic analysis based on RdRp sequences from selected dsRNA viruses showed that CNRV1 shared 31.9% sequence identity with Nigrospora oryzae unassigned RNA virus 1 (NoNRV1) and clustered with NoNRV1 and four other mycoviruses. These viruses are unassigned and distant from members of the family Partitiviridae, although they were previously considered partitivirus-like viruses. Thus, CNRV1 is a novel member of proposed genus "Unirnavirus", and is the first dsRNA sequence reported from a member of the phylum Zoopagomycota. This study extends our knowledge about mycoviruses in basal fungi.